Why does "the web" have to be a targeted platform? It isn't one in reality, Chromium, Safari and Firefox are different enough that you have to target them speci

Why does "the web" have to be a targeted platform? It isn't one in reality, Chromium, Safari and Firefox are different enough that you have to target them specifically. Seems to me the desire for having "web" as a platform isn't so you can also support a browser application. Its so you can make it a web app and call the job done.